Get the list of classes connected to the DB

It was quite troublesome before Rails4, but after Rails5
You can get a list of models connected to DB in ApplicationRecord.descendants.

For example, something like this.

model_list = ApplicationRecord.descendants

# If you want to output a list of class names
model_list.map { |v| v.to_s }
=> ["User", "Owner", "Blogs::Comment"]

Usage scenarios

• Batch processing
• If you are looking for a method that can be executed by the method xxx